My sister-in-laws action after the death of her son... normal?

Wow, what a terrible loss, I am very sorry. I find it hard to believe the mother of a 6 month old suffocated her child in his sleep by laying on him. When my daughter was an infant and she would sleep with me a lot, I was always aware she was there, and I never budged....even in a deep sleep, my subconscious knew my baby was beside me or in my arms. I have had numerous kittens and cats sleep with me, and I never roll over on them. I just don't understand how this could happen, and I absolutely would NOT be on Facebook and on the phone laughing. I realize people handle grief differently, and she still could be in a state of disbelief and shock. I have laughed at inappropriate times (funerals, etc) out of nervousness and I believe a form of disbelief....but if this happened to me, I know I would be so depressed and guilt-stricken that I would be on suicide watch. I think family should help get her into counseling....possibly inpatient. How is your brother handling this?